This invention relates to inflatable boats, and more particularly to such craft capable of being driven at high speeds by an engine such as an outboard motor.
A wide variety of collapsible and inflatable boats have been known for their virtues of compact storage when not in use, lightness in weight, and large measure of buoyancy. Those virtues have made such craft suitable for use as life boats, work boats that can be carried to places of use under circumstances that would be difficult to transport rigid boats, and for a variety of recreational uses.
One of the limitations characteristic of inflatable boats has been that the powering thereof by outboard motors of sufficient size to achieve planning speeds has met with only limited success. This is generally due to the inherently flexible nature of the craft, and particularly of the bottom or floor thereof which has a tendency to conform to the shape of the wave generated by the hull during movement through the water.
It is generally the current practice to stabilize the flexible bottom or floor of inflatable boats that are to be motor driven by installing a rigid backing therefor in the form of a plywood floorboard, either in one panel or formed of a plurality of sections in the interest of compact storage and ease of handling. While such floorboard reinforcement of the flexible bottom or floor provides good performance in use, the board or board sections are still not suitable for certain applications or uses of inflatable boats. In particular, where the inflatable boat must be dropped from an aircraft as a package in its deflated and furled condition, it has been found that the floorboard sections do not survive the impact of the package with water well enough for reliable use. This has been found to be true for sections formed of fiberglass reinforced plastic as well as for those formed of plywood.
In addition, even the use of sectional floorboard panels results in a storage package, when the boat is collapsed and furled, that is too large for certain situations, for example where it is necessary to pass the package out of a submarine through an escape hatch.
Other constructions have been proposed in an effort to render the fabric bottom or floor of an inflatable or folding boat sufficiently rigid for use of the boat with an outboard motor at relatively high speeds. These have included variations of inflatable keelsons or rigid frames formed of pipe. So far as has been determinable by applicants none of the prior constructions meet the required degree of rigidity in use, compactness of packaging for transport or storage, survivability of impact, or load and propulsion carrying capabilities that are desired for certain military applications.